This invention relates to a process for preparation of unsaturated oligomers or polymers by olefin metathesis of acyclic polyenes employing a catalyst composition comprising a transition metal chloride or ammonium salt, an organic tin compound or an aluminum halide reagent and an organic Lewis base wherein undesired side reactions such as double bond migration are minimized. With acyclic terminal polyene reactants, the process yields unsaturated oligomers or polymers with terminal carbon-to-carbon double bonds and at least one internal carbon-to-carbon double bond. These unsaturated oligomers or polymers with terminal double bonds are suitable for further functionalization or incorporation into other polymers.
Acyclic unsaturated compounds containing functional groups have been prepared by the olefin metathesis reaction. The metathesis of unsaturated ethers, amines and chlorides has been reported (K. J. Ivin, Olefin Metathesis, Academic Press, London, N.Y., 149, 1983) as the result of no inherent conflict between the functional groups and the metal carbene bond. However, it is reported that the interaction of the catalyst complex with functional groups of the subject olefin can be critical
As is well known, side reactions can occur during olefin metathesis reactions. These side reactions include alkylation, isomerization, cyclization and addition across double bonds present in the molecular structure.
This invention relates to the conversion of acylic polyene hydrocarbons and to a catalyst system for such conversion. In one aspect, this invention relates to the olefin reaction. In another aspect, it relates to the conversion of acyclic polyenes to other olefinic compounds having different molecular weights by disproportion or metathesis of olefins and to the oligomers and polymers derived therefrom which also have terminal double bonds and at least one internal carbon-to-carbon double bond.
The disproportionation or metathesis of olefins is a reaction in which one or more olefinic compounds are transformed into other olefinic compounds of different molecular weights. The disproportionation of an olefin to produce an olefin of higher molecular weight and an olefin of lower molecular weight can be a self-disproportionation reaction as propylene to ethylene and butene, or a double decomposition of two olefins or co-disproportionation of two different olefins to produce still other olefins.
The utility of the olefin disproportion reaction, commonly termed an olefin metathesis reaction, has been recognized as a means to obtain olefinic compounds bearing functional groups such as esters, ethers, halogens and others. However, inasmuch as the olefin metathesis reaction is an equilibrium reaction of unsaturated compounds, the usual consequences of an equilibrium reaction can be present, i.e., yields of the desired product can be low unless a suitable means of driving the reaction to completion can be utilized. Also, the catalyst present to initiate olefinic metathesis can initiate by-product reactions. The reverse of the olefinic metathesis reaction can occur wherein the reaction products self-metathesize to form other olefinic compounds. Terminal olefins have been found to self-metathesize rapidly such as in the industrial process for conversion of propylene to other products. The cis-trans configuration of the final product may be predominantly trans, or predominantly cis, or a mixture of cis-trans, depending upon reaction conditions, including the catalyst utilized.
The disproportionation of olefin bearing functional groups is an especially economically useful reaction in that the products bearing functional groups have been available and valuable for use in polymer formation and chemical transformations to yield industrially valuable products. The term functional groups as it relates to olefins as used herein denotes olefins containing functionality other than hydrocarbyl olefinic terminal unsaturates. Examples of functional groups previously available are esters, hydroxides, amines, halides. However, difunctionalized hydrocarbon oligomers and polymers containing at least one internal carbon-to-carbon double bond wherein the functional groups are terminal carbon-to-carbon double bonds have not been previously prepared from acyclic polyolefins by metathesis reaction except by a difficult and not easily-available catalytic process.
Telechelic polymers having terminal functional groups such as carbon-to-carbon double bonds usable for further reactions, i.e., cross-linking reactions or the construction of other defined polymer structures such as block copolymers, etc., are of great interest from the viewpoint of possible applications. A polymer halogen-terminated at both ends can be reacted with an unilaterally metal-terminated chain of another polymer to produce block copolymers. Hydroxy-terminated polymer chains can be cross-linked with di- and/or tri-polyisocyanates and/or analogous polyfunctional compounds such as acid chlorides of polybasic acids.
Telechelic difunctional polymers have been prepared in the past by termination of living polymers with anionic, cationic and metathesis polymerizations of cyclic olefins. Metathesis polymerizations of cyclic olefins can restrict the availability of products available to those which can be prepared from a relatively few cyclic olefins, typically of from about 5 to about 9 carbon atoms. Difunctional polymers derived from cyclic olefins can be limited in functional groups to those of the precursor cyclic olefins. With acyclic olefins, the olefin metathesis reaction with cleavage and reforming of carbon-to-carbon double bonds and the redistribution of alkylidene moieties leads to a random product distribution at equilibrium (Kirk-Othmer, Ency. Chem. Tech., 597, 3rd Ed., Vol. 8). Difunctional telechelic hydrocarbon oligomers/polymers produced via anionic or free-radical polymerizations of acyclic olefins typically are mixtures of polymer structures. For example, alpha-omega difunctional polybutadienes prepared by anionic or free-radical polymerization of butadiene contain mixtures of 1,4- and 1,2-polybutadiene structures, have molecular weights of 1000-4000 and are terminated with hydroxy or carboxy functionalities. Typically, the functionalities are less than difunctional, the functionality number being less than 2, and greater than difunctional, the functionality number being greater than 2.